1. Field of the Invention
The present invention is related generally to combustion processes and, more particularly, is directed towards a method and apparatus for synergistically reducing pollutant emissions while simultaneously increasing the efficiency of combustion. Even more particularly, the present invention is directed towards a method for enhancing the production of NO+ during combustion, and for separating, removing and extracting same for later processing into a valuable product.
2. Description of the Prior Art
Today, nitrogenous fertilizer is mainly derived from ammonia synthesized in the Haber-Bosch process from methane gas. In fact, in 1974, nearly 15% of all methane consumed in the United States went for the production of nitrogenous fertilizer. By the year 2000, it is estimated that five times as much fertilizer will be required, but the source of such fertilizer is not yet resolved.
Nitrogenous fertilizer is naturally formed in large quantities during an electrical lightning storm as a result of the formation of significant quantities of nitrogen oxides, NO.sub.x, which are in turn formed whenever the temperature of air is raised substantially. Man-made electric arcs have also been used to produce NO.sub.x, but this technique has been discarded in favor of others which require less energy.
NO.sub.x is also quite readily formed during high temperature combustion involving fossil fuels and air. NO.sub.x formation by this technique has heretofore been recognized as being potentially quite useful, as, for example, a feedstock for nitrogenous fertilizer. See, for example, the following articles:
"Japan's NO.sub.x Cleanup Routes", Ushio, S., Chemical Engineering, July 21, 1975, pp. 70, 71;
"Bottoming - Cycle Engines", Lindsley, E.F., Popular Science, January, 1976, pp. 82 - 85, 130 - 132;
"NO.sub.x Abatement for Stationary Sources in Japan", Ando, J., Tohata, H., and Isaacs, G.A., Environmental Protection Agency, Office of Research & Development, EPA-600/2-013b, January, 1976; and
"SO.sub.2 and NO.sub.x Removal Technology in Japan -- 1976", Ando, J. Environmental Technical Information Center, Japan Management Association, 3-1-22 Shiba Park, Minato-ku, Tokyo, Japan, February, 1976.
However, to the best of my knowledge, no practical, effective technique has yet been proposed for capturing the NO.sub.x formed from a combustion process.
Moreover, since NO.sub.x itself is notoriously toxic and is well recognized as a severe pollutant, efforts are presently directed towards either preventing the formation of NO.sub.x during combustion processes, or towards removing same once formed. The former technique, known in the art as combustion modification, attempts to inhibit the formation of NO.sub.x by operating at reduced combustion temperatures with fuel-air mixtures that are as air-lean as possible. Unfortunately, operating under such conditions inevitably results in a lower energy conversion efficiency which, in turn, wastefully increases fuel consumption.
The second technique mentioned above is known in the art as flue gas treatment wherein NO.sub.x is removed from the cooled flue gas, after it has already been formed, by either catalytic reduction to nitrogen and oxygen or by absorption in a suitable material. These types of controls, while somewhat effective, are unfortunately quite expensive to operate and maintain, since either an expensive catalyst must be replenished, or the sludge resulting from absorption must be disposed of in an environmentally acceptable manner.
While flue gas treatment controls are generally utilized in conjunction with some form of combustion modification program, present day controls for NO.sub.x rely chiefly upon inhibiting the formation of NO.sub.x. This is believed due to the fact that once NO.sub.x is formed, it is practically indestructable, i.e., no known process can, by itself, adequately reduce or capture the NO.sub.x before it is emitted into the ambient atmosphere.
It therefore may be appreciated from the foregoing that a technique which not only reduces NO.sub.x pollutant emissions, but increases combustion efficiency while also providing a ready source of NO.sub.x for later transformation into a useful product, would be extremly valuable. In other words, if the NO.sub.x emitted with the stack or exhaust gases from a combustion process could be effectively collected, its role would be reversed from that of a noxious pollutant to that of a valuable resource, for example, as a feedstock for the production of nitrogenous fertilizer.